Regarding the rotary actuators known from DE 19950582 C1 and DE 102010002621 A1 for e.g. disk valves in beverage filling systems of this type, the raceways in the guide grooves of the piston are planar and the bushes arranged on the ends of the transverse axis are configured with a cylindrical external circumference. This principle requires positioning the bushes and, if appropriate their bearings on the ends of the transverse axis, for example by means of securing rings or the like so that the bushes during operation of the rotary actuator do not exit e.g. outwardly from the guide grooves. During operation, however, high specific surface pressure occurs between each bush and the raceways of the guide groove. The high surface pressure may result in an early wear. The assembly effort for the required axial securing of the bushes is inappropriate.
The object of the present disclosure is to provide a rotary actuator of the type mentioned in the introductory part, which is characterized by a reduced surface pressure of the bushes and a reduced assembly effort as well as a disk valve with improved operating behavior and a beverage filling system with a reduced maintenance effort.
The cambering and the undercut of the raceway interacting with the cambering increase the contact area between the bush and the raceway, resulting in reduced surface pressure and less wear. Further, during operation, a secure positioning of the bush and an extensive force transfer between large areas occur, which as well has a positive effect on wear and durability. Due to the form-fit between the cambering and the undercut, a separate axial securing of the bushes is omitted, which considerably reduces the assembly effort.
The beverage filling system in relation to the disk valve with this rotary actuator, among other things requires low maintenance.
Regarding an appropriate embodiment, the bush is either double-conically or convexly, and in at least one example, spherically cambered, and the undercut of the raceways either runs double-conically or concavely curved, and in some examples, following a circular arc section. This geometric configuration is simple in terms of manufacturing, contributes to the optimum reduction of the surface pressure and to the reliable axial guidance of the bush.
Regarding an appropriate embodiment, the bush, may via a roller bearing or plain bearing, only be loosely fitted to the end of the transverse axis, e.g. up to a transverse axis shoulder. The bush is axially positioned on the end by form-fitting between the cambering and at least one raceway undercut, without additional aids or assembly steps during the assembly of the rotary actuator.
The track roller with pressed-in plain bearing only needs to be fitted on the transverse axis, which causes less assembly effort.
Particularly appropriate, approximately in the middle between both guide groove ends, each guide groove may have a bush assembly opening, which is at least accessible from the outer circumference of the piston. The assembly opening is usable in order to mount at least the bush on the end of the transverse axis or to replace it rapidly in the event of wear, without having to manipulate tools or securing elements. Thereby, the assembly opening is practically placed approximately in the middle between the two guide grooves, thus, in a region of the guide grooves, in which due to the course of the guide grooves the torque to be transmitted is relatively moderate so that there, the problem of the surface pressure between the raceway and the bush is non-critical, although there the contact area in the raceway somewhat decreases.
The assembly opening is appropriately configured in such a manner that one side of the undercut is removed arcuately in each raceway up to approximately the base of the undercut and corresponding to the contour of the outer circumference of the bush. The temporary lateral interruption of the undercut of the raceway at this point, approximately in the middle between the guide groove ends, has no negative effect on the functionality, since the bushes are moved through this area under relatively moderate load and cannot drop out.
The piston may be appropriately a plastic molded part, and in at least on example, an injection molded part, for example of reinforced polyoxymethylene. This plastic is only an example of a plurality of possibilities and in addition to high wear resistance, offers favorable friction conditions.
In a symmetrical configuration of the rotary actuator, for example, the effective distance of the torque supports from the axis is enlarged for receiving the torques generated by the cambered bushes and the undercut raceways by an approximately rectangular outer cross section of the torque supports with longer rectangular sides, which are approximately tangential to the axis, by parallel shorter rectangular sides, and by guides open to the outer circumference of the piston. The rectangular outer cross-section increases the bending resistance modulus in the direction tangential to the axis, strengthens the anchorage area of the torque support, and increases in interaction with the open guide in the outer circumference of the piston the effective distance to the axis, by means of which distance the torques are received and removed, which are transferred, for example in case of an axis-symmetrical configuration of the rotary actuator, having two bushes, from the cambered bushes and the undercut raceways into the piston.
The torque support, if appropriate, could be fixed at the inner wall of the housing, namely either only there or also on the cover and/or base of the housing. Furthermore, in a different embodiment of the rotary actuator, a single torque support and/or only one bush engaging the guide groove on the transverse axis could be sufficient.